Cyanosis is defined as:

Cyanosis is specifically characterized by a bluish discoloration of the skin, which occurs when there is insufficient oxygen in the blood or when blood flow is compromised. This condition can be seen in various medical situations, such as respiratory or cardiovascular issues, where oxygen transport is impaired. The bluish tint is most noticeable in areas where the skin is thinner, like the lips, fingertips, and mucous membranes.

Understanding the significance of cyanosis is crucial in medical practice, as it can be a key indicator of underlying health problems that require prompt attention. The other options describe different skin conditions: redness can indicate inflammation or infection, yellowing typically refers to jaundice often linked to liver dysfunction, and healthy skin color does not provide a clear clinical indicator of any condition.